WASHINGTON – Federal counterterrorism agencies are on high alert for a potential retaliatory attack on U.S. soil afterU.S. and Israeli forceslaunched strikes on Iran thatkilled the nation'ssupreme leader,Ayatollah Ali Khamenei, and other top officials.
The FBI and the Department of Homeland Security have both announced they are on war footing, as theyhave been in the pastover whether U.S. strikes, ordered by PresidentDonald Trump, on Iranian targets would prompt the Tehran regime and its proxy forces to seek revenge.
And while officials from both agencies declined comment to USA TODAY on March 1 about their heightened operations, veteran Iran watchers said there is good reason for them to be worried.
Iran launched retaliatory drone and missile strikes against American and Israeli targets after the joint U.S.-Israeli attack. Iran said its enemies would be "decisively defeated." Photos show reported attacks in Bahrain and Qatar. Smoke rises after the state news agency reported missile attack on the service center of the U.S. Fifth Fleet, following strikes by the United States and Israel against Iran, in Manama, Bahrain February 28, 2026, in this still image obtained from a video." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />
See Iran's retaliatory attacks on US military sites in the Middle East
Iran launchedretaliatory drone and missile strikesagainst American and Israeli targets after the joint U.S.-Israeli attack. Iran said its enemies would be "decisively defeated." Photos show reported attacks in Bahrain and Qatar.Smoke rises after the state news agency reported missile attack on the service center of the U.S. Fifth Fleet, following strikes by the United States and Israel against Iran, in Manama, Bahrain February 28, 2026, in this still image obtained from a video.
"Iran has developed this capability to carry out attacks abroad over many years," including in the United States, former FBI and Treasury Department counterterrorism official Matthew Levitt said. "If there was ever a time the regime would want to act on it, it would be now."
Already, Iran has responded with awave of retaliatory strikesacross the Middle East, including targeting countries hosting U.S. military bases like Bahrain and the United Arab Emirates. IranianPresident Masoud Pezeshkianvowed March 1 that "bloodshed and revenge" is Iran's "legitimate right and duty."
ThreeAmerican service membershave been killed and five others have been seriously injured in the ongoing conflict.
The Iranian regime has a long history –dating back at least 46 years– of assassinations and other terrorist plots on U.S. soil and against Americans overseas.
Those include plots disrupted by the U.S. against Iranian dissidents, andagainst Trumpand his former National SecurityAdviser, John Bolton, in response to a 2020 military strike that killed Iranian military leaderGen. Qassem Soleimani.
The United States wenton high alertlast June 22 overconcerns of retaliationfrom Tehran after the bombingof three Iranian nuclear sitesa day earlier.
Major U.S. cities from New York to Los Angelesstepped up their security, and the U.S. government issued warnings to U.S. citizens at home and abroad.
More:US sanctions Iranian officials for plot to kill John Bolton, other Trump officials
Washington's intervention in the so-called "12-day war" last year between Iran and Israel prompted the FBI and Department of Homeland Security toissue terrorism advisory warningsof potential Iranian attacks in the U.S.
And it spurred the FBI to pull many agents from one of Trump's top priorities, immigration and mass deportation efforts, back to counterterrorism in anticipation of potential attacks, Levitt wrote in an article for theU.S. Army's Combating Terrorism Centerin August.
At the time, federal officials advised their state and local government counterparts to be especially vigilant for potential domestic plots in the United States. One DHSNational Terrorism Advisory System bulletinwarned that the "Iran conflict is causing a heightened threat environment in the United States."
The bulletin warned that terror plots weren't the only concern.
Cyberattacks against U.S. networks "by pro-Iranian hacktivists are likely," with other attacks possible by the Iranian government, the bulletin said.
Citing Iran's "long-standing commitment to target U.S. Government officials," the bulletin said "the likelihood of violent extremists in the Homeland independently mobilizing to violence in response to the conflict would likely increase if Iranian leadership issued a religious ruling calling for retaliatory violence against targets in the Homeland."
What are the FBI and DHS doing now?
On Feb. 28, FBI DirectorKash Patelsaid the bureau is "fully engaged on the situation overseas," and that he has instructed the FBI's Counterterrorism and intelligence teams, including its 200-plusJoint Terrorism Task Forcesacross the country, to be on high alert and to "mobilize all assisting security assets needed."
"Our JTTFs throughout the country are working 24/7, as always, to address and disrupt any potential threats to the homeland," Patel saidin an X post. "While the military handles force protection overseas, the@FBIremains at the forefront of deterring attacks here at home - and will continue to have our team work around the clock to protect Americans."
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Patel called on "everyone to please report anything that may seem suspicious to law enforcement" via the FBI's 1-800-CALL-FBI tip line andtips.fbi.govwebsite.
Homeland Security SecretaryKristi Noemsaid the Department of Homeland Security is on similar heightened alert for potential U.S.-based attacks.
"I am in direct coordination with our federal intelligence and law enforcement partners as we continue to closely monitor and thwart any potential threats to the homeland," Noemsaid in an X post.
Officials from both agencies told USA TODAY they could not comment beyond what Patel and Noem announced.
Decades of plots, assassinations and attacks
In 1980, Iranian operative David Theodore Belfield, who had changed his name to Daoud Salahuddin,allegedly assassinated a former aideto the recently deposed Shah of Iranin the Washington, D.C. suburbof Bethesda.
Ali Akbar Tabatabai, 49, the Shah's aide, had organized the Iran Freedom Foundation, a vocal group opposed to the new religious government led by the then-supreme leader, Ayatollah Ruhollah Khomeini.
Dozens of other plots over the years followed, both in the U.S. and against American targets oversea,according to congressional investigators.
U.S. prosecutors say those efforts ramped up significantly in the years following the Trump-ordered assassination of Soleimani, a major general in Iran's feared Islamic Revolutionary Guard Corps (IRGC) and commander of the IRGC international attack unit known as the Quds Force.
Since Soleimani's death in 2020, Iranian operatives have plottedattacks on Trump,Bolton, other U.S. officials and prominent Iranian dissidents, either alone or in concert with the IRGC's many proxy organizations including the Lebanese terror group Hezbollah.
In all, U.S. authorities have disrupted at least 17 Iranian plots in the homeland since Soleimani's death, Levitt wrote in his West Point article.
A murder-for-hire plot against Trump
In November 2024, federal prosecutors in the Southern District of New York charged three men in amurder-for-hire plotagainst a U.S. citizen of Iranian origin. One of them,Iran-based operative Farhad Shakeri, was also charged with being directed by Iran and the IRGC with "surveilling and plotting to assassinate" Trump in revenge for Soleimani's assassination, according to a Justice Department criminal complaint.
Also indicted wereCarlisle "Pop" Rivera, 49, and Jonathon Loadholt, 36, both of New York.
Another man withties to Iran, Asif Merchant, is currently on trial in New York, and accused of taking part in a 2024 terrorism attempt and plot to kill Trump.
Bolton, the former top Trump aide who has been one of Iran's top U.S. targets, said March 1 he could not comment on whether he is receiving special protection from the FBI or Secret Service as he has in the past.
"I just probably shouldn't get into anything about that," Bolton told USA TODAY. "I just have no comment on all that sort of thing."
Bolton said he was given numerous "duty to warn" intelligence alerts by the FBI in recent years following confirmed Iranian threats to his life because of his role in the Soleimani assassination.
Those were deemed so serious that the FBI asked the Biden administration for special Secret Service protection for Bolton beginning at Thanksgiving 2021. It lasted until Trump ordered it cancelled on his first day back in office in January 2025 because of a falling out between the two after publication of Bolton's tell-all memoir of his time in Trump's first administration.
But, Bolton said, "The whole counterterrorism apparatus ought to be on high alert at this point in the U.S., and in contact with our friends and allies around the world, because there's no doubt that Iran will – the regime will – try and use every mechanism they've got to retaliate for what's happening."
This article originally appeared on USA TODAY:FBI, Homeland Security on high alert after US attacks Iran